Earth science

What ancient eggshells can tell us about extinction

Rachel Sauer — Tue, 21 Jul 2026 19:55:38 +0000

What ancient eggshells can tell us about extinction Rachel Sauer Tue, 07/21/2026 - 13:55

Tiffany Plate

CU �ֲ��ý Professor Emeritus Gifford Miller contributed to a new study that delivers a more accurate understanding of the extinction of one of Australia’s oversized flightless birds

Some people collect albums. Or coins. Or stamps. CU �ֲ��ý Professor Emeritus Gifford Miller collects the eggshells of large extinct flightless birds.

That collection came in handy for recent research that’s helping scientists understand more precisely when Genyornis newtoni went extinct in Australia—and whether humans were responsible for their extinction.

Genyornis is a genus of large flightless birds that roamed the Australian outback alongside modern-day emus; they reached heights of about 7 feet and weights upwards of 500 pounds.

Gifford Miller has spent some 20 seasons in the field in Australia collecting the well-preserved eggshells of flightless birds. The samples were pivotal to recent research determining the extinction date of the continent’s largest flightless bird. (Photo: Gifford Miller)

While emus—which are unrelated to Genyornis—survived, the majority of other megafauna on the continent went extinct around the time humans arrived (or just shortly after).

“There was a really big uncertainty in Australia as to how we get precise, reliable ages on when the actual Genyornis extinction occurred,” says Miller, a professor emeritus of earth science who is also the director for the Center for the Geochronological Analysis of the Global Environment at the Institute of Arctic and Alpine Research (INSTAAR). “Radiocarbon dating wasn’t going to do it, and amino acid racemization wasn't going to do it at the precision we wanted.”

To get closer to the truth, Miller encouraged his colleague, Elizabeth Niespolo, a geologist at Princeton University, to try out a different method called uranium-thorium burial dating. The process relies on the eggshells to uptake uranium—which is plentiful in Australian soils—and then produce thorium as a byproduct of uranium decay.

The results of the research were published this summer in a new article in the journal Quaternary Science Reviews, which Miller co-authored.

The megafauna-human overlap

Previous dating methods posited that genyornis went extinct around 60,000–65,000 years ago. However, Niespolo found much different results.

“She thinks she has very firm extinction dates at about 45,000 years ago, which is quite a bit younger than a lot of other people think,” says Miller.

The date that humans arrived in Australia is also still up for debate, with some studies saying they showed up around 55,000 years ago, and others around 65,000 years ago (still a long time ago when the only way to reach the island at that time was via boat, Miller points out).

Either way, the new results would mean there was a very long period of time between the arrival of human colonizers and the extinction of genyornis.

“We’re basically left with two options: either there is a long overlap, which is unusual relative to almost all other human-faunal extinction overlaps, or the early human colonization dates are too old,” says Miller. “Both are plausible.”

Predation or fire?

Now, scientists are left to continue zeroing on that human arrival date, as well as the method by which humans managed to make so many species go extinct.

Genyornis newtoni was one of many species of megafauna that disappeared from Australia around the time of human colonization. (Illustration: Peter Trusler/Monash University)

“There are two options, and both have some strength behind them,” says Miller. “One of them would be predation, particularly of genyornis eggs.” Many eggshells were found with evidence of contact with fire, he says, meaning they were either cooked directly over a fire or discarded near one. “Clearly people were utilizing these eggs as a food source.”

The birds themselves might also have made their way to the dinner plate. “These are very big birds, much bigger than emu,” says Miller. “So, they would be a meal for a whole family for a week or two.”

For his part, Miller is partial to another theory: that humans impacted the landscape by systematic burning of vegetation that was genyornis’ primary food source.

“We have independent evidence from the emu—including a continuous time series from the present back through the extinction window—that shows the entire ecosystem shifted about 45,000 years ago in the central desert area where these birds are most common,” says Miller.

Leveraging the eggshells for further research

Miller is hoping that he and Niespolo might be able to use her now-proven dating methods on other eggshells in his collection to learn everything they can about the last 100,000 years or so on the continent.

“I have this tremendous geographic spread of samples from all across Australia,” says Miller, who hopes they might use that reservoir of material to determine whether the extinction dates changed based on location. “Did it happen earlier or later on the south coast? Or up in the far north near Darwin where the first people must have arrived?”

Miller also believes they can learn more about the historical temperature gradient of Australia using Niespolo’s dating methods on his collection.

“There are some interesting little tidbits that she and I are kicking around,” Miller says. “We’re looking to put together more projects that might capitalize on this amazing resource of samples I have.”

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CU �ֲ��ý Professor Emeritus Gifford Miller contributed to a new study that delivers a more accurate understanding of the extinction of one of Australia’s oversized flightless birds.

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Top photo: Gifford Miller

Project puts fossil records at the world’s fingertips

Rachel Sauer — Tue, 30 Jun 2026 21:41:51 +0000

Project puts fossil records at the world’s fingertips Rachel Sauer Tue, 06/30/2026 - 15:41

Tiffany Plate

A major digitization project at CU �ֲ��ý’s Natural History Museum is helping researchers around the world collaborate like never before

Imagine being able to see the hairs on a 45-million-year-old fly. Without a microscope. In a lab 5,000 miles away from the museum where it’s stored.

Public images with that level of detail are the result of a major digitization project that has been going on at CU �ֲ��ý’s Museum of Natural History for more than a decade. The museum team has been diligently snapshotting and recording data about the museum’s collections, then sharing them to open-source databases that are available to researchers around the world. These efforts, which span the Museum’s collections departments, reflect a shared commitment to making specimens and data more accessible for researchers around the world.

The museum’s Paleontology Department, specifically, has shared more than 1 million specimen records to the Global Biodiversity Information Facility (GBIF)—many with high-resolution images to accompany them—from across the museum’s collections.

“It’s been really key to getting our collection used more,” says Talia Karim, collections manager of invertebrate paleontology at the museum. “We’ve had graduate students in other countries find those images on GBIF and then request higher-resolution images they can publish in a paper.”

As collections manager of invertebrate paleontology, Talia Karim has led major projects to digitize the museum’s fossil collections and publish the resulting data so it can be used by researchers around the world. (Photo: Patrick Campbell/CU �ֲ��ý)

The project was made possible through the National Science Foundation’s Advancing Digitization of Biodiversity Collections (ADBC) funding opportunity, which was designed to advance scientific knowledge by improving access to digitized information in U.S. collections.

Now, with the help of a new grant, Karim is working with end users to refine their data output and make sure it’s as usable as possible for people looking to leverage these collections.

To that end, this April, Karim and her team hosted a workshop at CU, gathering paleontology collections managers from around the country, many of whom received funding from the ADBC grant to digitize their own collections.

“We brought all these people together to talk about what’s next,” says Karim. “How can we keep working together to digitize more data or improve the quality of the data to make sure it’s being used?”

The digitization process

With the help of CU graduate students, and some high-tech imaging systems, there are now nearly 57,000 invertebrate fossil records on GBIF that feature two-dimensional images, alongside information about the fossil’s geologic and geographic contexts.

Capturing those images requires a multi-step process. “We're putting a specimen under the camera, and then we're taking images at multiple focal depths,” says Karim. “Then we merge those so that you have a very small thing that's totally in focus in a 2D image.”

Because these are fossils, and don’t have any genetic data to share, researchers need to have a crisp, clear view of the specimen’s morphology in order for the fossil to be useful.

“That’s why it’s important to have those really in-focus, high-resolution photographs,” says Karim. “And some of the morphology on the fossil insects is incredibly preserved. You can see all the venation on the wings of a dragonfly. Or you can zoom in on a fly and see all these little hairs. And they're 45 million years old!”

Karim’s team made use of two NSF grants, Fossil Insect Collaborative and Cretaceous Worlds, to document not only the Museum’s fossil insect collections but also its Cretaceous Western Interior Seaway fossil collection, which features ammonites and clams that were left behind when Colorado was underwater 100 million years ago.

Putting data to good use

Now that those specimens are available on GBIF, they’re facilitating a lot more research connections. Last year Karim was contacted by a French graduate student who had discovered a fossilized ancient sawfly that was first discovered in Colorado’s Florissant Formation and is now part of the museum’s collections.

“He found more things he wanted to work on, and then he shared it with his lab mate, and his lab mate found things in our collection,” says Karim. “But as grad students, they weren’t going to come all the way here from France to look at one specimen.” Instead, Karim’s team was able to use their imaging equipment to take whatever custom high-resolution images they needed.

Karim also points out that having data from a huge number of specimens allows for a more automated aggregation of data to answer big questions about, say, global species distributions through time.

This image of an ancient picture-winged fly was taken from the museum’s fossil insect collections and is just one of more than a million entries CU has submitted to the Global Biodiversity Information Facility database. (Photo: CU Museum of Natural History)

"Museum collections allow us to ask questions that span hundreds of millions of years, revealing how life evolved and how ecosystems responded to a changing world,” says Carl Simpson, associate professor of earth science.

“Digitization allows those collections to power the science of the future,” Simpson adds. “And then by combining museum collections with artificial intelligence, we can accelerate the pace of biodiversity and evolutionary research."

In that vein, Simpson is leveraging the stellar imagery Karim’s team created, along with AI, to identify characteristics in bryozoans, a phylum of simple, aquatic invertebrate animals that he studies. “AI gives us new tools to ask questions at a scale that would have been impossible only a few years ago,” Simpson says.

Fine tuning their output

As co-PI of their current grant, Simpson is serving as a sort of end user test case for Karim’s team to see how the data is being used. But Karim is also gathering input from everyone involved in the process through a series of workshops.

The most recent workshop was the third such gathering planned to help execute Karim’s current Geosciences Open Science Ecosystem grant. The first, which took place in 2024, included paleontologists and researchers who helped Karim’s team determine how their digitized files could be more useful. “We asked, have we digitized the kinds of things that they need for their research?” Karim says. “Can they retrieve the kind of information that they need for their research? What’s missing?”

In 2025, the workshop brought together people who develop cyber-infrastructure tools for databases like GBIF. They shared some researcher feedback and asked them how they might address that feedback from an IT perspective to ensure their systems are actually user friendly. (Karim adds that often in academia systems get built without ever talking to the people who are using what's being built. “So, we're trying to bridge that gap a little bit!”)

Before Karim’s grant wraps up next spring, she and her team will integrate learnings from these information-gathering sessions into a “Paleo Data Roadmap,” featuring recommendations for developers of cyber infrastructure or data standards about how to increase data usability.

Karim looks forward to the increased connections—not just with her fellow collections managers, but from researchers around the world—that have resulted from their digitization efforts. “I love seeing the types of research that people are doing,” she says. “And I also really like helping people with their research. That makes me very happy.”

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A major digitization project at CU �ֲ��ý’s Natural History Museum is helping researchers around the world collaborate like never before.

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CU �ֲ��ý graduate student wins DOE award, joins NASA-DARES

Rachel Sauer — Tue, 16 Jun 2026 15:53:07 +0000

CU �ֲ��ý graduate student wins DOE award, joins NASA-DARES Rachel Sauer Tue, 06/16/2026 - 09:53

Kayleigh Wood

Earth science PhD candidate Catherine Fontana will pursue cyanobacterial biofilm research at the Lawrence Livermore National Laboratory

Catherine Fontana, a geobiology PhD candidate in the �ֲ��ý Department of Earth Science and the Interdisciplinary Quantitative Biology Program, was recently selected for the Department of Energy’s (DOE) Office of Science Graduate Student Research (SCGSR) award for her research on cyanobacterial biofilms.

The highly competitive program offers PhD candidates in various STEM fields the opportunity to advance their thesis research at one of DOE’s research facilities alongside a DOE national laboratory scientist. Additionally, awardees are eligible to receive a stipend for general living expenses and inbound and outbound transportation.

“The DOE SCGSR program allows me to study microbial processes using cutting-edge analytical techniques and world-class facilities that are a hallmark of the Department of Energy national laboratories,” Fontana says.

PhD candidate Catherine Fontana was recently selected for the Department of Energy’s (DOE) Office of Science Graduate Research (SCGSR) award for her research on cyanobacterial biofilms.

In the Department of Earth Science, Fontana is co-advised by stable isotope geochemist Boswell Wing and microbial physiologist Sebastian Kopf. Her research on cyanobacterial biofilms seeks to understand the connections between microbial physiology, mineral precipitation and stromatolite (a layered, rock-like formation built by microbial communities) formation using stable isotope geochemistry and experimental evolution.

From October 2026 to April 2027, Fontana’s SCGSR award will support her study at Lawrence Livermore National Laboratory in California, where she will work closely with Rhona Stuart, who leads the DOE’s MicroBiospheres Scientific Focus Area. The DOE laboratory offers Fontana the opportunity to leverage a stable isotope technique called NanoSIMS to track variation in stable isotope composition at the micron-scale level.

The project, “Tracking Carbon Flow in Cyanobacteria Biofilms and Their Mineral Byproduct,” explores “how carbon moves through cyanobacterial biofilms and the extent to which this carbon contributes to minerals they make, like carbonate, that eventually turns them into rocks, like stromatolites,” she explains, adding that her work is especially meaningful in the context of developing next-generation biotechnologies in which cyanobacteria and their biofilms may be an innovative foundation for bioeconomy products.

Charting the future of NASA astrobiology

Additionally, after a highly competitive open-call application, Fontana was selected as one of nine early-career scientists to serve on the 49-member NASA-DARES Task Force 2. Composed of members of the astrobiology community, NASA-DARES, or NASA’s Decadal Astrobiology Research and Exploration Strategy, will serve as a roadmap for the organization’s future astrobiology research, which aims to understand life’s origins, evolution and distribution across the universe.

Since January, NASA-DARES Task Force 2 has been building on the nine major focus areas—which include comparative planetology to understand habitability and astrobiology in society, among others—identified by Task Force 1 by gathering community input through virtual webinars and public discussions. Task Force 2 is currently synthesizing community perspectives into a document outlining contemporary astrobiological interests, available opportunities and the diverse scientific approaches and disciplines in motion across NASA Science.

As the executive secretary of Focus Area 8, Early Career and Workforce Development, Fontana has worked with her team to solicit and synthesize community input regarding how NASA can best support early-career astrobiologists and develop the field over the next decade.

“As an early career researcher passionate about the future of astrobiology, I am profoundly honored to be part of NASA-DARES,” says Fontana. “As the only early-career member of the ‘Early Career and Workforce Development’ focus area, I feel a strong responsibility to represent early-career voices and perspectives. This role provides me with a unique opportunity to help shape the chapter’s findings and contribute to pivotal conversations about the future of astrobiology.”

NASA-DARES is still soliciting feedback: The public comment period for NASA-DARES is open this month and close July 2. The final NASA-DARES document will be shared at the American Geophysical Union (AGU) meeting in December.

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Earth science PhD candidate Catherine Fontana will pursue cyanobacterial biofilm research at the Lawrence Livermore National Laboratory.

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Earth science

What ancient eggshells can tell us about extinction

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What ancient eggshells can tell us about extinction

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CU �ֲ���ý graduate student wins DOE award, joins NASA-DARES

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CU �ֲ��ý graduate student wins DOE award, joins NASA-DARES